Fogging devices are devices which disperse liquids such as liquid insecticides into the air in minute droplets to form a fog or mist. The fineness of the droplets contributes the propensity of the dispersed liquids to remain suspended in the air where, in the case of insecticides, they may contact the largest possible number of insects.
The effective fogging devices are those which produce a fog in the form of a cold liquid mist. These devices usually employ the centrifugal effects of rapidly rotating disk, cone or wafer to atomize the liquid which is pumped against it. Frequently, the rotating device, such as a disk, is provided with a plurality of axially projecting slots or comb-like teeth near the perimeter thereof to break the liquid into the small droplets. The finer and more closely spaced the teeth are, the finer the generated droplets will be.
It has been found that a more suitable and finer fog can be produced by replacing the slotted disk with a porous ring-like material. Effective dispersal of the liquid, however, through such a porous material requires greater centrifugal force than with a slotted or toothed disk. This greater force must generally be produced by a higher rotational speed. Applicants have found that rotating such material at a high rate of speed of, for example, above 23,000 RPM at a speed of, for example, 28,000 RPM will, with a disk of approximately 21/2" in external diameter, produce a superior fog effective for insecticides and many other foggable liquids. Motors which will rotate the fogging disks of porous material at speeds of near 30,000 RPM with sufficient power to disperse the liquid have not been provided in the prior art.
Use of these devices to disperse insecticide along roadways usually requires their mounting on vehicles. Achieving these high rotational speeds and high power has been particularly lacking for vehicle mounted insect fogging devices where electric motors must operate on the power provided by a 12 volt battery or battery powered electrical system of a vehicle. Providing alternative means of powering the motors and employing motors which achieve the power and speed through gearing and other mechanical arrangements present expensive and unreliable solutions to the problem.
Accordingly, there is a need for a high speed electric motor, for example, one which will operate in the vicinity of 30,000 revolutions per minute, which will produce sufficient power, for example, approximately 0.2 horsepower, while operating directly from a 12 volt power supply of a vehicle.